An animal is a living creature that breaths, feed and moves about. There are thousands of different kinds of animals, from tiny ants to giant whales, and they live everywhere on Earth. Humans are animals too.
VERTEBRATES AND INVERTEBRATES
Scientists have divided animals into two groups: those with backbones and those without. Animals that do not have backbones form the largest group. They are called invertebrates. Animals with backbones are called vertebrates. To make animals easier to study, scientists have split vertebrates and invertebrates into smaller groups. Some main animal groups are fish, insect, amphibian, reptile, bird and mammal. Animals in the same group have things in common, such as the way they look or how their bodies work.
There are nearly two million known kinds of invertebrates. They all look very different from one another, but most are small creatures. They may be broadly divided into those with jointed legs and those without joint legs. Invertebrates with jointed legs form the largest group of invertebrates. They have segmented bodies and hard skin on the outside, which they shed from time to time as they grow. They include animals such as crabs, lobsters, centipedes, scorpions, spiders and insects . Invertebrates live all over the world, from the dark ocean depths to high mountain tops. They were the first group of animals to appear on Earth, around 1000 million years ago.
Invertebrates without jointed legs can be divided into animals that are worm-like and those which are not worm-like. Animals that are worm-like include worms with segmented bodies and worms without segmented bodies. They include animals such as jellyfish, leeches, earthworms, starfish, octopus and snails. The key below shows the classification of invertebrates. Vertebrates are divided into the groups amphibians, fish, reptiles, birds and mammals because of their different characteristics. Amphibians are soft-skinned animals that live on land and water. They are cold-blooded vertebrates. Frogs, toads, newts and salamanders are amphibians. Fish are animals with scales. They live in fresh water or sea water. Most fish have bony skeletons, However fish such as the sharks and rays have soft bones. Reptiles are animals that breathe through their lungs and they have hard and leathery scales. Crocodiles, turtles, snakes and lizards are reptiles. Most of them live on land; the others live in water. Birds are the only vertebrates with feathers. They lay eggs with shells. Mammals are animals with hair or fur and they breathe through their nostrils and lungs. All mammals, except the duck-billed platypus and the spiny anteater, reproduce by giving birth to live young. Another way to group vertebrates is to go according to what they eat. Animals that eat only plants are called herbivores. Animals that eat meat are called carnivores. Animals that eat both plants and animals are called omnivores. We are omnivores, and so are chimps, bears, pigs and rats. Scientists also group animals according to the temperature of their bodies. Warm-blooded animals, such as mammals and birds, keep almost the same body temperature whatever the weather outside. Cold-blooded animals are different. Their body temperature changes depending on the weather outside. Amphibian, insects, reptiles and most fish are cold-blooded. Glossary Amphibian: any of numerous cold-blooded vertebrates belonging to the class amphibia , eg frogs, toads and newts, the adults of which live partly or entirely on land but return to water to lay their eggs, which hatch to form fish-like larvae or tadpoles that breathe by means of gills. Reptile: any cold-blooded scaly vertebrate animal, e.g. lizards, snakes, tortoises, turtles, crocodiles, alligators, and many extinct species, including dinosaurs and pterodactyls. Mammal: any warm-blooded, vertebrate animal characterized by the possession in the female of mammary glands which secrete milk to feed its young, e.g. a human, monkey, whale, etc. Segmented: a part, section or portion.
CLASSIFICATION
Categories of living things:
There are thousands of different kinds of animals, from tiny ants to giant whales, and they live everywhere on Earth. Humans are animals too.
AND
INVERTEBRATES
Invertebrates with jointed legs form the largest group of invertebrates. They have segmented bodies and hard skin on the outside, which they shed from time to time as they grow. They include animals such as crabs, lobsters, centipedes, scorpions, spiders and insects . Invertebrates live all over the world, from the dark ocean depths to high mountain tops. They were the first group of animals to appear on Earth, around 1000 million years ago.
Invertebrates without jointed legs can be divided into animals that are worm-like and those which are not worm-like. Animals that are worm-like include worms with segmented bodies and worms without segmented bodies. They include animals such as jellyfish, leeches, earthworms, starfish, octopus and snails. The key below shows the classification of invertebrates.
Vertebrates are divided into the groups amphibians, fish, reptiles, birds and mammals because of their different characteristics. Amphibians are soft-skinned animals that live on land and water. They are cold-blooded vertebrates. Frogs, toads, newts and salamanders are amphibians. Fish are animals with scales. They live in fresh water or sea water. Most fish have bony skeletons, However fish such as the sharks and rays have soft bones. Reptiles are animals that breathe through their lungs and they have hard and leathery scales. Crocodiles, turtles, snakes and lizards are reptiles. Most of them live on land; the others live in water. Birds are the only vertebrates with feathers. They lay eggs with shells. Mammals are animals with hair or fur and they breathe through their nostrils and lungs. All mammals, except the duck-billed platypus and the spiny anteater, reproduce by giving birth to live young.
Another way to group vertebrates is to go according to what they eat. Animals that eat only plants are called herbivores. Animals that eat meat are called carnivores. Animals that eat both plants and animals are called omnivores. We are omnivores, and so are chimps, bears, pigs and rats.
Scientists also group animals according to the temperature of their bodies. Warm-blooded animals, such as mammals and birds, keep almost the same body temperature whatever the weather outside. Cold-blooded animals are different. Their body temperature changes depending on the weather outside. Amphibian, insects, reptiles and most fish are cold-blooded.
Glossary
Amphibian: any of numerous cold-blooded vertebrates belonging to the class amphibia , eg frogs, toads and newts, the adults of which live partly or entirely on land but return to water to lay their eggs, which hatch to form fish-like larvae or tadpoles that breathe by means of gills.
Reptile: any cold-blooded scaly vertebrate animal, e.g. lizards, snakes, tortoises, turtles, crocodiles, alligators, and many extinct species, including dinosaurs and pterodactyls.
Mammal: any warm-blooded, vertebrate animal characterized by the possession in the female of mammary glands which secrete milk to feed its young, e.g. a human, monkey, whale, etc.
Segmented: a part, section or portion.
Rainforest Animals
Getting Started
Need Help?